My arena is made out of 10' panes. Originally I slid one leg over a 3' piece of debar that had been pounded into the ground. Looked good and mostly straight for about 2 years and the more I used it as a turn out area the more bowed out it became to the point that one long side was maybe 9" shorter. The only solution was to take the long sides down and start again. I drove t post every other joint. You should be able to go every third or even fourth panel if you only use it to ride in. Make sure every t post is below the top rail of the panel. Zipties were the fastest way to secure the panels to the posts. Do not do square corners. Rounded corners are stronger, you will save 4 -8 panels and if you get off on the long sides, iit's simple to get that 4th side closed off. Easier to add a little more curve to the corners and done.